Automatic diaphragm regulator for a photographic camera



Dec. 19, 1961 Filed Feb. 20, 1958 J. DURST AUTOMATIC DIAPHRAGM REGULATOR FOR A PHOTOGRAPHIC CAMERA 2 Sheets-Sheet 1 INVENTOR. Julius Dunl- BYW W #wt) Dec. 19, 1961 3,013,479

J. DURST AUTOMATIC DIAPHRAGM REGULATOR FOR A PHOTOGRAPHIC CAMERA Filed Feb. 20, 1958 2 Sheets-Sheet 2 INVENTOR. Julia; Dan! 3,013,479 AUTOMATIC DHAPHRAGM REGULATOR FOR -A PHQTOGRAPHIC CAMERA Julius Durst, Bressanone, Italy, assignor to Julius Durst and Firma Durst See. p. A., Fabrica Nlachine ed Apparechi Fototecnici, Bolzano, Italy Filed Feb. 20, 1958, Ser. No. 716,416 Claims priority, application Italy Feb. 21, 1957 Claims. ((31. 95-10) This invention relates to an automatic device for regulating the diaphragm of a photographic camera in accordance with the ambient illumination detected by a photoelectric exposure meter incorporating a movable galvanometer element, and more particularly relates to such anautomatic device which is operatively associated with a moving picture camera. 1

In the past the diaphragms of moving picture cameras have been manually adjusted to changing light conditions with reference to a separate exposure or light meter. The desirability of having this adjustment performed automatically has led to the use of battery-operated electric motor-driven devices for adjusting the lens diaphragm. In these devices electrical contacts or switches are operatcd in accordance with the indicator position of a galvanometer connected to a photoelectric cell to change the direction of movement of the motor. The reaction of this type system is so slow, however, that the adjustment of the diaphragmis not fast enough to keep up with rapidly changing light conditions. Similar diaphragm adjusting devices operated by spring mechanisms incorporate similar disadvantages.

An object of this invention is to provide a continuously operating automatic exposure regulating device which can be associated with the diaphragm of a photographic camera, particularly a moving picture camera, in which substantiall3 no delay occurs between the times that it detects the position of the movable galvanometer element accordingly adjusts the diaphragm.

In accordance with this invention an automatic device for regulating the lens diaphragm of a photographic camera includes a light meter incorporating a movable element, for example, the indicator or pointer of a galvanometer. A pair of separate detecting elements contact the galvanometer in such a Way that one detecting element moves the diaphragm in the closing direction while the other element moves the diaphragm in the opening direction. T he force for driving the automatic device is, for example, derived from a spring mechanism which transports the film. However, electric or pneumatic devices may also be used.

These detecting elements are, for exampie, mounted upon a carriage which is reciprocated by an eccentric which is, for example, rotated by the driving element of the camera. moved periodically indicator or pointer.

This galvantometer or pointer is, for example, shaped toprovide a knife-edged contact surface which faces the detecting arms of the detecting elements. The flat base of this knife-edge contact surface is disposed adjacent a support bar which is also, for example, reciproc-ated 180 into contact with the galvanometer out of phase with the movement of the carriage. The

counter moving drives ofthe carriage and support bar are,

The detecting elements are accordingly Patented Dec. 19, 1am

for example, taken from a pair of eccentrics mounted upon a single shaft which are respectively engaged with the carriage and the support bar through yokes. This counter moving or counter pressing arrangement coordinates the movement of the detecting elements and the support bar in such a way that there is no mechanical load imposed on the galvanometer or pointer while it is clamped between the support bar and the detecting element. This freedom from load and shock is provided because the pointer is clamped between the support bar and detecting elements without being deviated from its plane or path of movement. In the clamped position the support bar is, therefore, maintained motionless whereas the detecting arms of the detecting elements move a sufiicient distance to cause the actuating arms of the detecting elements to adjust the position of the lens diaphragm.

Novel features and advantages of the present invention will become apparent to one skilled in the art from the reading of the following description in conjunction with the accompanying drawings in which similar reference characters refer to simiiar parts and in which:

FlG. l is a cross-sectional side view in elevation of one embodiment of this invention;

FIG. 2 is a cross-sectional front view in elevation of the embodiment shown in FIG. 1;

FIGS. 3, 4 and 5 are front views in elevation of a portion of the embodiment shown in FIG. 1 in various phases of operation; and

FIG. 6 is a front view in elevation similar to FEGS.

3-5 of a modified embodiment of this invention.

in FIGS. 1 and 2 is shown a photographic camera, for example a moving picture camera [1, including a photoelectric light meter c, which automatically detects the ambient illumination. When moving picture camera I) is started, a shaft d revolves, for example with a rotational frequency substantially equal to the visual trequency or a fraction of it. This rotates a pair of eccentrics d mounted upon shaft d at the same frequency. Support bar e is coupled with eccentrics d through extensions or yokes .2 This reciprocates support bar e toward and 'way from the path of movement of light meter or galvanometcr pointer At the same time substantially rectangularly shaped carriage g with detecting elements it and i movably mounted uponit are moved toward the other side of galvanometer pointer f. EX- tensions or yoke g of carriage g which engage a pair of eccentrics d are also mounted upon shaft d, for example out of phase with eccentrics d Eccentrics d engaged with carriage g are referred to herein for convenience as eccentrics, and eccentrics d; are referred to as additional eccentrics since carriage g is the primary detecting agent of this device. All parts associated with carriage gare, therefore, designated as primary parts while parts associated with support bar e are designated as additional parts. i

The contact end of galvanometer pointer f is constructed and arrange for example, to include a knife-edge contact surface It whose knife edge faces detecting elements It and i. Detecting elements 12 and i include similar but oppositely disposed detecting arms I1 and i which contact and detect the position of galvanorneter pointer j". The other 0* actuating arms 1' and k of elements i and h contact a portion of the adjusting means of diaphragm n, forexample, an extension 3 of diaphragm ring [mount- 3,9 3 ed upon lens tube m. Detecting elements 11 and i are, for example, rotatably mounted at opposite sides of carriage and, for example, are equidistantly disposed outside the extremities of the path of movement of galvanometer pointer 7'.

The contacting surfaces of actuating arms I1 and i are constructed and arranged in a curved form which is, for example, constructed and arranged to precisely govern the position of diaphragm ring I in accordance with the position of the indicator 1 of light meter c over its full range of travel.

Camera b also includes an exposure triggering element (not shown) which is, for example, operativcly engaged with the film transport device exposure releasing device (both also not shown) and with eccentric shaft 0.. Movement oi the triggering element initiates rotation of shaft d prior to transport of the film and prio to opening of the shutter of the camera which automatically adjusts the diaphragm in accordance with the light meter and ambient illumination before the triggering clement actuates movement and exposure of the film.

In the free position of the diaphragm n shown in PEG. 2 for example, actuating arms I1 and i rest against fixed stops q while diaphragm and adjusting ring I and projection y are free. Diaphragm fl and adjusting ring 1, however, incorporate enough frictional resistance to remain in a set position.

inis free condition occurs with the frequency of measuring which is, for example, substantially equal to the vision frequency or more rapid. At the same time galvanometer pointer is free of detecting elements It and i and support bar 2 to allow it to move in accordance with variations in the ambient illumination.

When the counter pressing or counter movement of elements it and i with bar e commences and galvanometer pointer bearing k is clamped between support bar e and detecting arms I1 and i diaphragm ring I is automatically moved by adjusting arms I1 and i to a position corresponding to the position of movable element pointer 1 when it is clamped. Diaphragm n then remains in this et position until the succeeding measuring impulse moves it to another position corresponding to the changing light value at that time.

FIGS. 35 only include certain elements in order to distinctly indicate the functions of detecting elements It and i and support bar a and the manner in which the diaphragm n is adjusted in accordance with the position of knife-edged contact surface it of pointer f.

In FIG. 3 knife-edged contact surface k of galvanometcr pointer f is close to the left-hand end of its path of movement where it, for example, indicates a brightly illuminated condition. etecting elements It and i in this position are accordingly moved to the left in order to close diaphragm n.

in FIG. 4 light meter 0 indicates a medium or average amount of light; and levers h and i are symmetrically disposed to adjust diaphragm n to an average size.

in PEG. 5 exposure meter 0 indicates very little or dim light which position knife-edged bearing surface k at the right end or beginning of its scale or path of movement. Detecting elements h and i are, therefore, deviated to the right to correspondingly open diaphragm n to its maximum opened position.

FIGS. 3-5 also show a tension spring p reacting between actuating arms I12 and i of elements it and i to maintain them in contact with fixed stops q as indicated in FIG. 1 when galvanometer pointer f is free.

In PEG. 6 is shown a modified embodiment of this invention in which detecting elements It and i contact projection y, of diaphragm ring I through separate actuating levers s and 0. Actuating levers s and 0 are respectively maintained in contact with detecting elements i and h by tension springs p reacting, for example, between fixed portions of the camera and actuating levers s and 0. Levers s and 0 make contact with detecting elements i dand h, for example, through spherical projections :7 and 0 which ride along adjusting surface i and I1 Adjusting surfaces I1 and i of detecting elements 11 and i are curved, for example for precisely adjusting lens diaphragm n in accordance with the position of galvanorneter indicator surface It over its entire range of movement.

What is claimed is:

1. An automatic device for regulating the lens diaphragm of a photographic camera comprising a light meter incorporating a movable element, said diaphragm including an adjusting means, a pair of separate detecting elements, said detecting elements each including a detecting arm constructed and arranged to contact said movable element of said light meter, said detecting elements respectively including adjusting arrns'constructed and arranged to contact said diaphragm adjusting means for respectively opening and closing said diaphragm, movable mounting means supporting said detecting elements in positions in which their detecting arms are disposed adjacent said movable element of said light meter for actuating movement of said respective adjusting arms in opposite direction relative to said diaphragm adjusting means when said detecting arms contact said movable element of said light meter, said movable element being rotated in a plane by said light meter in accordance with the ambient illumination, 21 support bar disposed parallel to and adjacent said plane, said detecting elements being rotatably mounted at the other side of said plane upon a carriage, reciprocating means moving said carriage substantially perpendicularly towards and away from said plane to periodically clamp said movable element between said detecting arms and said support bar for causing said diaphragm to be adjusted in accordance with the position of said movable element when it is clamped, and resilient means reacting against said detecting elements in a direction to maintain said adjusting arms clear of said diaphragm adjusting means when said carriage moves away rom said plane.

2. An automatic device as set forth in claim 1 wherein the side of said movable element adjacent said detecting arms includes a knife-edged surface for precisely governing the displacement of said detecting arms when it contacts them.

3. An automatic device as set forth in claim 1 wherein said carriage comprises a substantially rectangular element, said reciprocating means includes a rotating eccentric, and wherein a yoke is attached to said bar and operatively engaged about said eccentric for causing said bar to reciprocate in response to rotation of said eccentric.

4. An automatic device as set forth in claim 1 wherein additional reciprocating means moves said support bar towards and away from said plane of movement of said movable element 180 out of phase with said reciproca ing movement of said carriage to periodically clamp said movable element between said support bar and said dctecting arms.

5. An automatic device as set forth in claim 4 wherein said additional reciprocating means includes an additional eccentric means which is out of phase with said eccentric means associated with said carriage, and extensions and additional yoke means couple said support bar to said additional eccentric means.

6. An automatic device as set forth in claim 1 wherein pivots rotatably mount said detecting elements upon said carriage, said pivots being equidistantly disposed outside the opposite extremities of travel of said movable element, and said detecting arms extend from said pivots towards each other.

7. An automatic device as set forth in claim 1 wherein said diaphragm adjusting means is a diaphragm ring including a projection, and said adjusting arms bear directly upon said projection.

8. An automatic device as set forth in claim 1 wherein said periodic actuating means operates at a rate provid ing four measurements per second.

9. An automatic device as set forth in claim 1 wherein positions of said movable element over the entire range of said adjusting arms include curved surfaces which are movement of said movable element of said light meter. constructed and arranged to precisely coordinate the diaphragm settings with the various positions of said mov- References Cited m the file of thls Patent able element over its entire range of travel. 5 UNITED STATES PATENTS 10 An automatic device as set forth in claim 1 where- 2,838,985 Burger et a1 June 17, 1958 in said detecting elements each include separate rotatably mounted detecting arms and actuating levers, said arms FOREIGN PATENTS and levers contacting each other through a curved sur- 821,026 France Aug. 17, 1937 face, said curved surface being constructed and arranged 10 842,887 Germany Nov. 20, 1952 to precisely coordinate the diaphragm setting with the 909,294 Germany Apr. 15, 1954 

